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11-24-2009, 05:05 PM   #1
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Aperture ring fluidity

If I posted this thread anywhere else in the world, I'd probably be considered certifiably insane. I'm counting on my fellow fanatics here on our forum not to judge me so harshly. I'm into the old M42 Takumars partially because of their unmatched fluid focusing action. The best of them also duplicate this in their aperture ring movements. Some, however, are too notchy in their action. Case in point is a mint condition 24mm Super-Multi-Coated Takumar I just purchased. The aperture ring is just notchy enough to annoy me, especially compared to the Super version of the same focal length I also have. It doesn't seem to be a matter solely of breaking in over the course of time & repeated use, although that obviously contributes to the eventual desired effect, but the fact that I own mint condition examples of some lenses that have obviously seen almost no use & have buttery smooth aperture action supports the theory that some just come out of the factory this way. My question is, is there any way i can facilitate the smooth action I'm seeking from notchy lenses by taking the lens apart & applying some type of lubricant or filing down some of the notches, or is this something I just have to live with?


Last edited by raymeedc; 11-24-2009 at 06:22 PM.
11-24-2009, 05:15 PM   #2
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In most Pentax lenses, the "notchy" action is controlled by a steel ball bearing.

I imagine replacing the ball bearing with one of different size will change the action. I've done that out of neccessity: the original ball bearing gots lost when I dissembled the lens.

The ball bearings don't cost much. Get different sizes and see which one works best for a particular lens. You can buy them here: Micro-Tools
11-24-2009, 05:24 PM   #3
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QuoteOriginally posted by SOldBear Quote
In most Pentax lenses, the "notchy" action is controlled by a steel ball bearing.

I imagine replacing the ball bearing with one of different size will change the action. I've done that out of neccessity: the original ball bearing gots lost when I dissembled the lens.

The ball bearings don't cost much. Get different sizes and see which one works best for a particular lens. You can buy them here: Micro-Tools
I wonder if they purposefully changed bearing types to match what they perceived to be the desired effect at different points in the manufacturing lifetime of a particular model. It would be interesting to know if certain years produced uniformly notchy or smooth action, depending on the bearings they were using at the time.
11-24-2009, 05:44 PM   #4
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It might not matter today with TTL metering, but at some point you want the aperture detents to be positive in locating the correct aperture.

Buttery smooth also implies lack of a positive notch and perhaps difficulty knowing your aperture setting ewithout looking.

11-24-2009, 05:54 PM   #5
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The bearing(s) may be worn or one of a pair might be missing. There might also be a lack of lubrication due to age. I have a bunch of older lenses and some have very smooth aperture rings (all three of my Rikenons and the Mamiya/Sekor 55/1.8) and some are fairly notchy (the Helios 44M (expected), the Pentax-K 55/1.8, and the Pentax-M 50/1.7). For the most part, it is not a functional problem so I have resisted the urge to tear them apart.

Ironically, the smoothest in my quiver is the FA 35/2 when off the "A" setting. This plastic-bodied lens has a silken aperture action.

Steve
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